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This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
I was so fed up of not being able to differentiate the left from the right in the Beomaster 3000 output amplifier (and Beocenter 3500) that I made this small drawing. (indeed, knowing that a wire is "brun" at the output does not really help since they're all "bruns" ! It identifies all transistors and the emitter resistors. It serves as a complement to the schematic. (Please tell me if there's any mistakes)
The front is on top. Note that the left is right and the right is left. (Well, it depends on your position) Also note the reversed position of the output transistor attached on the back, depending on the channel output.
I'm posting it here, in case it would be useful to somebody else... (By the way, mine ended up as a "Feu d'artifice" after a full recap. (TR 49 now shows continuity between Emitter and collector). That will be for another day...
Guillaume
Thanks, very nice indeed.These circuits are not all too stabile from factory and it's not unusual to see one start up with a very brief whine or buzz, that is practicallyimpossible to get rid of.This is a good example of an amplifier, where one shouldn't use the trendy low-ESR caps, that seems to be the newest fashion craze.It will up the risk of self-osciallation considerably (and the frequency of such).
If you removed the brown leads, it's important to remember that some don't go in straight lines as the layout almost suggests, someshould actually cross eachother. I can't tell from the photo if you got this right.
Martin
Dillen: If you removed the brown leads, it's important to remember that some don't go in straight lines as the layout almost suggests, some should actually cross eachother. I can't tell from the photo if you got this right.
If you removed the brown leads, it's important to remember that some don't go in straight lines as the layout almost suggests, some
should actually cross eachother. I can't tell from the photo if you got this right.
On mine, no wire are crossing whatsoever. I haven't touched any of them. The soldering seems original too.
But you're right: I was curious about the brown wire crossing: after searching on the web I've found out some photos that actually shows the collector and emitter wire of TR45 and 57 (small transistor "glued" with thermal paste on the chassis), crossing each other. Here's a view of mine, showing all the straight wires:
I'll have to check if they are placed correctly. Another possibility is that they change the transistor in the course of production, or they changed the way it is fixed to the chassis. On mine, the head is turned upside down, so all the legs are bent. I can't remember how they are fixed in my BC3500 so I can't compare though. This is definitely something to be aware of. I guess my copy is an old production: all output transistors are from RCA instead of Motorolla. It's a shame I blew on of them. (Or I guess so: I had a value of 0.15V between one of the emitter resistor for the right channel during bias adjustment, which makes for about 1 Amp. The fuses have blown (1 Amp). But isn't these output transistors supposed to handle much higher values?
It's correct that there can be several slightly different versions so at least check that everything is connected correctly.What is the serial number and build series of this unit ?
Here:
Also, "225$" is stamped under the wooden case.
The wire for the main plug seems original. However, the plug doesn't. But it does seem to be old, so it's probably been in Canada since a long time. I wonder if B&O really sold the thing this way for the North American market or if someone just had it imported and then converted it himself.
The marking on the front aluminum panel seems to be washed away. Probably because of the sun.
Thanks, that's one of the later production individuals.
Yours could have another track layout at the vertical rear board, but this photo shows, howthey usually are:
http://muare1.vcmedia.vn/images/2013/08/15/mr_208009_c5ce490d33aac123.jpg
I have the 3000-2 Type 2402 serie 20, serial no. 25540, which also has the brown wires crossed to TR45 and TR57.
For ease of identification, I have put the component values on the right channel as per the board layout photo attached.
Guillaume, I noticed that you posted an extract of a clean circuit diagram. Mine was removed from the main dealer when it was first put in for service and they refused to give it back to me. Is there any chance that you can scan a clean copy for me. I have downloaded the 2Nr Beomaster 3000 service manuals from this site, unfortunately the voltages at various test points are totally illegible and I do need these for troubleshooting. Component value identifications is not a problem, as this can be obtained from the actual components fitted.
Norman
**EDIT**
I've sent you a PM,
I might also have sent it for upload on this site.
Dillen: Thanks, that's one of the later production individuals. Yours could have another track layout at the vertical rear board, but this photo shows, howthey usually are: http://muare1.vcmedia.vn/images/2013/08/15/mr_208009_c5ce490d33aac123.jpg Martin
If I remember right, thats the same layout as in my BM 4400
Collecting Vintage B&O is not a hobby, its a lifestyle.